Nozzle diaphragm



April 2,-1940. G.' s. WARREN erm. 2,196,045

Nozzmz DIAPHR'AGH Filed June 5' 1958 I waff HezeKiah Ha; h,

Glenn B. Warren Patented Apr. 2, 1940 UNITED STATES NozzLE DIAPHRAGMGlenn B. Warren, Niskayuna, and 'Hezekiah Haigh, Scotia, N. Y.,assignors toGeneral Electric Company, a corporation of New YorkApplication June 3, 1938, Serial No. 211,592

3 Claims. (Cl. 253-78) The present invention relates to nozzlediaphragms such as are used in an elastic fluid turbine for conductingelastic fluid to bucket wheels. More particularly, the invention relatesto the type of nozzle diaphragms which includes a nozzle structurehaving inner and outer bands and a `plurality of spaced nozzle bladessecured to the bands and forming nozzle passages for directing the flowof elastic iiuid to a bucket wheel. An arrangement of this kind isdisclosed in the patent to H. A. Lacey, No. 1,932,278, issued October24, 1933, and assigned to the same assignee as the present invention.The outlet edges of the nozzle blade are thin and when exposed to thehigh pressures and temperatures in modern elastic fluid turbines theyare subjected to excessive strains and stresses which may lead to damageof the thin edges especially in case the thin edges are integrallymounted or formed with bands or side walls.

The object of our invention is to provide an improved nozzle diaphragmwhereby strains and stresses to which the outlet edges of the nozzleblades are subjected are considerably reduced.

For a consideration of what We believe to be novel and our invention,attention is directed to the following description and the claimsappended thereto in connection with the accompanying drawing.

In the drawing, Fig. 1 illustrates a sectional View through a turbinenozzle diaphragm and bucket Wheel arrangement embodying my invention;Fig. 2 is a view along line 2 2 of Fig. l; and Fig. 3 is a View alongline 3-3 of Fig. 2'.

The arrangement comprises a nozzle structure with a plurality ofcircumferentially spaced noz- Zle blades I0 having thin outlet edges IIand inner ends secured to or integrally formed with an inner band I2 andouter ends secured to or integrally formed with an outer band I3. Thesecuring of the ends of the blades to the inner and outer bands may beaccomplished by Welding in the manner set forth in the afore-mentionedpatent to Lacey. The inner band I2 is seated in the present arrangementin a recess I4 of a disk I5 and united with the latter by a weld I6. Theouter band I3 is seated in a recess I1 of a solid outer ring I8 andunited therewith by a Weld I 9. The nozzle structure forms passagesbetween adjacent nozzle blades for conducting elastic' fluid to a bucketWheel which has a p1urality of buckets 2| with inner ends suitablyfastened to a disk or wheel 22 and outer ends connected by a shroud band23. 4

In order to prevent excessive strains and near said thin outlet stressesfrom` being setup in the thin 4outlet portions II of the nozzle bladesI0, the end portions of the inner and outer bands I2 and I3 portions I Iare made resilient. In the present example the inner and outer bandshave end portions 24 and 25 which are reduced in thickness. `These thinportions 24 and 25 are not directly secured to the disk and ringby theWelds I6 and I9 respectively and thus they are free to expand in radialdirection. An arrangement of this kind is described in the applicationof John H. Doran filed on the same date as the present application.

The nozzle structure with the inner and outer bands after assembly withthe disk and the outer ring form large grooves to be filled by Welds I6and IS. In order to facilitate the provision of the weld I6 We providein accordance with our invention a welding shield which may be in theform of a ring 26 uniformly spaced from the reduced end portion 24 ofthe inner band I2 and forming therewith a gap or slot 2l. Similarly, awelding shield or ring 28 is provided to facilitate the provision of theweld I9 and to form a gap or slot 29 with the reduced portion 25 of theouter band I3. These welding shields 26 and 28 have another importantfunction in that they form sealing surfaces in cooperative relation withsealing strips 3l) and 3| secured to the disk 22 and the shroud band 23respectively of the bucket Wheel,

After Welding, the welding shields or rings 26 and 28 form a unitarystructure with the inner and outer bands and it is clear that the sameresult may be accomplished by making these welding shields an integralypart of the inner and outer bands and thereafter machining the slots 21and 29 into end portions of these bands.

In other Words, solid' bands such as disclosed, for instance, in theabove patent to Lacey may be used and in order to provide flexibility oftheir end portions, these portions may bemachined to form slots near thevthin edge portions of the lnozzle blades. Thus, applicants bands andWelding shields together constitute band structures which have an edgeportion circumferentially slotted to render resilient a part of suchportion secured to the thin outlet portions of the blades.

Having described the method of operation of our invention, together withthe apparatus which we now consider to represent the best embodimentthereof, we desire to have it understood that the apparatus shown isonly illustrative and that the invention may be carried out by othermeans.

What We claim as new and desire to secure by Letters Patent of theUnited States is:

1. A nozzle diaphragm including a band structure, a plurality of nozzleblades with thin outlet edges and ends secured to the band structure,tbe portion of the band structure secured to and in proximity to thethin outlet portions being circumferentially slotted to render such bandresilient and thereby to eliminate excessive strains and stresses in thethin outlet portions.

2. A nozzle diaphragm comprising a plurality of nozzle blades havingthin outlet edges, a band united with the ends of the blade, a solidmember forming a seat for the band, the band having a y portion reducedin thickness secured to the thin outlet portions, a welding shielduniformly spaced with the reduced band portion, and a weld uniting theband with the solid member and the Welding shield.

3. A nozzle diaphragm comprising a plurality 0f spaced nozzle bladeshaving thin outlet edges, inner and outer bands secured to the ends ofthe blades, said bands having portions reduced in thickness near theoutlet edges of the blades, inner and outer welding shields formingnarrow gaps with the reduced inner and outer band portions, a disk, aweld uniting the inner band and Welding shield with the disk, a ring,and a weld uniting the outer band and welding shield with the ring.

GLENN B. WARREN. HEZEKIAH HAIGH.

